This invention relates generally to mass data storage devices and, more particularly, to solid-state random access memory (RAM) mass data storage devices.
Many computer applications, such as graphics imaging and animation, seismic data processing, weather forecasting, design automation, and scientific simulation, require large system memories for processing. The system or main memory of a computer is typically a limited array of solid-state static and/or dynamic random access memory (SRAM and/or DRAM) chips which provides temporary storage for applications programs and data during processing. A rotating magnetic memory, such as a hard disk, is typically used for permanent storage of the programs and data because it is nonvolatile and less costly per megabyte than solid-state random access memory (RAM).
Various techniques have been developed to overcome the restrictions imposed by the limited size of main memories. One such technique is virtual memory, which is a memory addressing technique that allows a computer to function as if it has more main memory than it really does. Virtual memory stores some parts of the applications programs and data on hard disk and some parts in the actual or physical main memory. When particular program instructions or data are needed that are not in the physical main memory, the instructions or data are loaded from the hard disk. However, hard disks have much slower access times than solid-state RAM memories, and latency time is significantly increased with this technique.
As refinements in semiconductor fabrication techniques have reduced the unit cost and increased the unit density of solid-state RAM memory devices, solid-state memory devices have been increasingly used in applications that were once the domain of hard disks. One such application is a solid-state mass data storage device that is configured as a RAM disk. A RAM disk emulates a hard disk and effectively allows virtual memory to be stored in solid-state RAM memory, thus significantly decreasing latency time. However, solid-state mass data storages devices do not presently provide the high densities and large memory capacities that are required for many computer applications. Accordingly, there has been a need for a high-density, high-capacity solid-state mass data storage device. The present invention clearly fulfills this need.